Field
The present disclosure relates generally to communication systems, and more particularly, to timing source selection and deselection for distributed device to device (D2D) synchronization.
Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of a telecommunication standard is LTE. LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. LTE may support direct device-to-device (peer-to-peer) communication.
In a D2D communication system where the user equipments (UEs) may not have access to any source of synchronization (e.g., wireless access network (WAN) based, global positing system (GPS) receiver based, etc.), the UEs may achieve synchronization through use of a distributed protocol. In such a protocol, resources for synchronization (e.g., synchronization channel resources) may be allocated on a slow time scale (e.g. once every second) to reduce battery expenditure as well as the amount of resources used for the synchronization. Further, multiple UEs may transmit in multiple broadcast resources available in the synchronization channel, and may receive the transmissions on these resources to obtain timing structure information, frame structure information, time and frequency corrections, other channels' allocations, etc.
In a densely populated D2D communication system, these synchronization channel resources may be heavily reused as all the UEs attempt to transmit in each occurrence of the synchronization channel. If all the devices transmit in the sync channel, there may be problems with scaling of resources, uncontrolled interference to the timing information broadcast (TIB) transmissions, etc.
As such, a system and method to improve synchronization channel design for densely populated D2D communication systems may be desired.